Hi,thanks for using healthcare magic
I am sorry for the distress these conflicting results must be causing you and your wife.
If the recent blood HCG
levels are negative then it would confirm the urine results and the ultrasound
results. This would mean that your wife is not pregnant at this time. Normally urine HCG can be detected 6 to 12 days after fertilisation and at this point they should indicate a positive result if your wife was pregnant.
It is possible that the result 5 weeks ago was a falsely positive result, though this is rare, it has been documented to occur.
It is unlikely to be a miscarriage
since you indicated there was no history of cramping abdominal pain
I hope this helps and wish you both the best